Is it possible to put multiple names in one string?

Question

I just started learning C++ and I'm currently following a tutorial on YouTube.

I thought it was fun to make a very simple 'access' program. If I type in my name it says, "Welcome!" If I type in another name it says, "access denied". It worked perfectly fine, but then I wanted the program to say "Welcome!" to two different names. So, I wanted to add a second name in the string, but I couldn't figure out how to do that. I googled a lot but I couldn't find anything. In the end, I came to string name = ("Joe", "Sean");, but here, it was only valid for Sean. I just can't figure out how to put multiple names in one string and make them both work. I hope you can help me, here is my code:

#include <iostream>
#include <cmath>
#include <string>

using namespace std;




int main()
{
    string name = ("Joe", "Sean");
    string input;
    cout << "What is your name?\nMy name is: ";
    cin >> input;



    if(input == name){
        cout << "Welcome, "<< input <<"! ";

    } else {
        cout << "Access denied";
    }



    
    return 0;
}

You're trying to only greet people whose names appear in a set of names? — erip, Oct 25 '20 at 18:24
"Following a tutorial on Youtube" is the worst possible way to learn C++. C++ is the most complicated general purpose programming language in use today. The only way to thoroughly learn C++ is from a fully vetted and edited textbook, any clown can upload a video to Youtube, that says anything he wants to say. A C++ textbook will teach you how to use arrays and vectors, which is what you need to do for this task. — Sam Varshavchik, Oct 25 '20 at 18:25
To extend what @SamVarshavchik wrote there, the art of googling is posing the right question, and the art of research is questioning the source you have. (i.e. find a better source to learn C++ from) — Tony Tannous, Oct 25 '20 at 18:26
I think you should follow that tutorial (or some [good C++ book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) ;] )a bit further until they cover vectors, arrays and other stl-containers. Right now you've arrived at a solution that is definitely not what you want, see also: [How does the comma operator work?](https://stackoverflow.com/questions/54142/how-does-the-comma-operator-work). And I think just giving you some code would confuse you more than if you learned it on your own. — Lukas-T, Oct 25 '20 at 18:27
What you probably want is a `std::vector names = { "Joe", "Sean" };` and `std::find()`. — πάντα ῥεῖ, Oct 25 '20 at 18:28
What πάνταῥεῖ said, though it looks like you want `std::any_of`. — cigien, Oct 25 '20 at 18:33
Learn about what the comma operator does. It's not what you expect. Also a std::string can hold a single string. — drescherjm, Oct 25 '20 at 18:55

score 2 · Answer 1 · answered Oct 25 '20 at 19:51

This is a way to do it using a vector of strings, so you can adapt easily with more names :

#include <iostream>
#include <vector>

using namespace std;

void printMessage(string message)
{
    std::cout << message << std::endl;
}

int main()
{
    vector<string> names{"Joe", "Sean", "Paul"};
    string input;
    cout << "What is your name? " << endl;
    cin >> input;

    for (string name : names)
    {
        if (name == input)
        {
            printMessage("Welcome!");
            return 0;
        }
    }
    printMessage("Access Denied!");

    return 0;
}

gkaf · Accepted Answer · 2020-10-25T22:05:54.110

The problem is in the string variable "name". You need an array of strings, not a single string.

This is an example implementation:

#include <iostream>
#include <cmath>
#include <string>

using namespace std;

int main()
{
    string names[] = {"Joe", "Sean"};

    string input;
    cout << "What is your name?\nMy name is: ";
    cin >> input;

    for (int i = 0; i < end(names) - begin(names); i++) {
      if(input == names[i]){
          cout << "Welcome, "<< input <<"! " << endl;
          return 0;
      }
    }

    cout << "Access denied" << endl;

    return 0;
}

You encountered some quirky features of C++ in the approach you are using to initialize your string variable:

string s1 = ("Joe"); // creates a string "Joe"
string s2 = ("Joe", "Sean"); // creates 2 strings, "Joe" and "Sean", and the variable s2 stores only the latter!

For more details on the different methods for initializing variables there has been an interesting discussion in this previous question.

I would recommend using `std::size(names)` instead of `end(names) - begin(names)` - or `std::distance(begin(names), end(names))` - or better, use a range-based for-loop: `for(auto& name : names) { if(input == name) ...` — Ted Lyngmo, Oct 26 '20 at 15:38

Is it possible to put multiple names in one string?

2 Answers2